It is often necessary due to various spinal disorders to surgically correct and stabilize spinal curvatures, or to facilitate spinal fusion. Numerous systems for treating spinal disorders have been developed.
One method involves a bone fixation system including a pair of elongated members, typically spinal rods, longitudinally placed on the posterior spine on either or both sides of the spinous processes of the vertebral column. Each rod is attached to various vertebrae along the length of the spine by way of bone fixation or bone anchor assemblies, e.g. pedicle screws. The body of the pedicle screw often has a rod-receiving channel and receives a locking cap to secure the spinal rod to the pedicle screw.
To facilitate insertion of the spinal rod into the rod-receiving channels of the pedicle screws, pedicle screws have been developed wherein the body is separate from and pivotable with respect to the bone anchor (commonly known as polyaxial pedicle screws).
It is desirable to develop a bone fixation system and assemblies that are simple for a surgeon to use.